1. Field of the Invention
The present invention is related generally to an engine monitoring system and, more specifically, to means for maintaining an oPerational history of a turbine engine during its lifetime in a way which is insensitive to the separation of the turbine engine from related monitoring equipment during the operational lifetime of the engine.
2. Description of the Related Art
It is known by those skilled in the art to use microprocessors or microcomputers in conjunction with the control of engines. For example, U.S. Pat. No. 4,677,558, which issued to Bohmler et al on June 30, 1987, describes a method and system for controlling the operation of an apparatus or engine, particularly an internal combustion engine. The Bohmler et al patent describes a system which permits the change of data, to be used in a fixed program carried out by a microprocessor in accordance with a stored program, upon the change in operating characteristics of a controlled apparatus such as an internal combustion engine. The system uses an erasable programmable read-only memory which is external to the microprocessor. This external memory forms a combined address and data memory having at least one address field and a vector field. A constant data field and a table, or function data field, are part of the external memory and the data fields contain data to be addressed directly through the address field or via the vector field for not only a single type or series of apparatus, such as internal combustion engines, but also additional engines or engine characteristics. For example, the data can be changed to account for engine aging. In order to run the program by the microprocessor, with a changed or aged engine, it is only necessary to change the address of the data in the data field and/or the vector field to provide different output data for any given programming step. The Bohmler et al patent does not anticipate the transfer of information from the microprocessor to an erasable programmable read-only memory during the operation of the engine. In fact, the Bohmler et al patent specifically describes the off-line data changing methodology when engine related parameters change. In addition, the Bohmler et al patent does not describe the erasable programmable read-only memory as being attached to the engine.
U.S. Pat. No. 4,523,286, which issued to Koga et al on June 11, 1985, describes an apparatus for making diagnosis of a valve device in a turbine system. The Koga et al patent describes a diagnostic apparatus for performing a diagnosis of a valve device in a turbine system which comprises at least one of a pressure sensor for sensing hydraulic pressure in a hydraulic cylinder for driving a valve body of the valve device and a position sensor for sensing the displacement of the valve body. The system also comprises a processing device for processing the output signal from the above mentioned sensors. The processing device has an offset computing device which receives a signal representing the actual operating state of the valve device obtained on the basis of the output signal from the sensor and a signal corresponding to a reference value obtained from the normal operating state of the valve device. The offset computing device is operable to compute the offset between the signals received. A judging device is provided for judging as to whether or not there is a symptom of a sticking of the valve device in accordance with an output signal from the offset computing device.
German patent DE 3410675 C1, which issued to Hafner et al, describes a processor control system for an engine which utilizes a processor having the engine operating parameters stored in a memory device which is fitted to the engine. The Hafner et al patent describes a system in which particular operating details for an internal combustion engine are incorporated into a read-only memory which is applied to the side of the internal combustion engine on a thermally insulating mounting. The program can be divided between separate read-only memories and applied to different parts of the engine. The internal combustion engine is controlled by a standard processor unit which is provided with electrical power by the normal engine battery. The processor is linked to the engine data storage and provides an optimum control system for the engine and its accessories. The stated advantage of the invention described in the Hafner et al patent is that a universal processor can be used in conjunction with individual read-only memories wherein the individual read-only memories provide necessary modifications that are applicable to each type of engine. The Hafner et al patent describes a system which attaches a read-only memory to an internal combustion engine for the purpose of providing a unidirectional data transfer from the read-only memory to the motor controller. It does not describe or suggest the on-line storage of historic engine operating parameters in the read-only memory for maintaining a lifetime history of the internal combustion engine. In fact, it specifically describes the memory as a read-only memory and not as a programmable read-only memory or an electrically erasable programmable read-only memory.
For the purpose of maintaining a lifetime turbine operations log for the turbine engine, it is desirable to provide a means by which information can be stored in a manner which is permanently associated with the engine being monitored regardless of whether or not the engine is separated from its control unit or the vehicle, such as an aircraft, with which it is originally associated. While the prior art describes several systems in which engine related information is stored prior to engine operation for purposes of maintaining a source of engine parameters, none of the prior art patents described above teaches the concept of providing a means for storing historical data relating to the operation of the engine in such a way that the stored data can be changed during the on-line operation of the engine.